Different types, styles, and constructions of containers have long been known and used in the past. Likewise, many different materials have been used in the manufacture of containers. For example, the common paper bag, comprised of four side walls, and a bottom wall formed from overlapping and glued flaps of paper, is a well known construction eminently suitable for its purpose. Cardboard containers, such as boxes, are also quite common and have been provided in various configurations and constructions for a variety of purposes. Plastic containers, such as bottles for holding liquids or thin film plastic bags for disposing of trash, are likewise well known and variously constructed and used.
Containers formed of plastic materials have significant advantages in comparison with prior paper or cardboard containers. For example, plastic containers are strong, resilient, long-lasting, and inert to most items disposed in the container. They are also suitable for containing and confining fluid materials. Additionally, plastic containers are currently produced at extremely low cost and are therefore well suited for disposal after use. Common plastic containers of the thin film type, however, have a number of disadvantages in comparison with paper or cardboard containers in that the latter are generally self-supporting or free-standing in their intended shape. On the other hand, containers formed of thin plastic film are generally not capable of assuming or maintaining a predetermined shape.
Further, paper, cardboard and plastic bags are not suitable in many environments for use alone and thus must be used in conjunction with other containers or support structure. For example, it is common practice to provide a container formed of a relatively rigid plastic material and then to line the container with a paper or thin film plastic bag. Paper bag liners, of course, sometimes lack sufficient strength, resilience and the capacity to contain and confine liquid materials. Plastic bag liners, on the other hand, are easily punctured by the contents of the container. In certain applications, for example, trash disposal, it is also necessary to lift the paper or plastic liner from the supporting container and replace it with a fresh paper or plastic bag liner. Paper or plastic bag liners frequently break or tear when lifted from a supporting container. Tearing is often caused by depositing material into a plastic liner. Frequently, in the case of paper liners, tearing occurs by a weakening of the bag in the areas where liquid has absorbed. Additionally, when such paper or plastic liners fail, the supporting container usually must be cleaned (particularly if the liners were intended to be used as trash receptacles).
Thin film plastic bags or containers are also typically used by themselves--that is, without any additional supporting structure. However, because these bags are not self-supporting or free-standing, it is usually quite difficult to fill them in the absence of any ancillary supporting structure (i.e., since the bags tend to collapse upon themselves without such supporting structure). For example, thin film plastic bags are commonly used for disposing of leaves. However, filling these bags with leaves or even maintaining the bag open for filling purposes is difficult because the bags will collapse absent a supporting structure.
According to the present invention, however, a container is provided which includes a self-supporting side wall. This side wall is, moreover, thin-walled--that is, the gauge thickness of the sidewall is sufficiently thin so that the sidewall is normally non-self-supporting. Nonetheless, the self-supporting characteristics are imparted to the sidewall according to the present invention by means of unitarily formed and longitudinally extending corrugations. These corrugations therefore serve to rigidify the sidewall along its longitudinal extent.
The sidewall extends upwardly from a relatively thicker base portion. This base portion is present so as to provide stability to the containers of this invention so that the self-supporting capabilities of the sidewall may be fully realized.
Preferably, the upper edge of the side wall terminates in an annular rim which lies in plane substantially transverse to the longitudinal dimension of the corrugations. The rim serves to maintain the sidewall in an opened configuration and thus more easily allow waste, articles and the like to be deposited into the container's interior space (i.e., the space bounded by the sidewall). The rim is preferably of the same thickness as that of the sidewall but is formed into an outwardly directed U-shaped configuration. The outward appearance of the rim will therefore be an aesthetically pleasing smooth convexity.
A terminal flexible section is preferably joined to the rim. This flexible section is of sufficiently thin gauge (e.g., approximately the same wall thickness as the sidewall) so that it may be folded downwardly and lie adjacent the exterior periphery of the sidewall. However, when the containers of this invention are desired to be closed, this flexible section may then simply be gathered together at the container top and tied.
The containers of this invention are, moreover, of a one-piece (i.e., unitary) construction. That is, the base portion, sidewall portion and, if present, the rim and flexible terminal section are each unitary with one another. This unitary construction is most conveniently achieved by means of an extrusion blow-molding method using suitably configured mold platens (to be described later).
These, and other, aspects and advantages will become more clear after careful consideration is give to the following detailed description of the preferred exemplary embodiments of the present invention.